Superstar singer Rihanna surprised London Underground travellers by catching the Jubilee Line to the first of 10 sold-out concerts at the O2 Arena, reports said. The 23-year-old Barbadian chatted with fans and posed for pictures in a crowded carriage, telling one that she didn't know "how you guys do it", according to the Evening Standard. As one of the world's biggest pop stars, Rihanna is more used to travelling in private jets and limousines but turned up unannounced to travel by public transport to Wednesday's performance. Lisa-Marie O'Keeffe, a singer, wrote on a website: "I met Rihanna on my way home, told her she was crazy for taking the Tube she said, 'Dunno how you guys do it', the Standard added. "(She) was taking the Tube to her own gig at the 02, how funny? She was lovely and chatty but I wasn't quick enough for a snap with her. I had to double look, her accent was more of a give away." Adrienne Amado, from St John's Wood, told Nick Ferrari on LBC that Rihanna, who was accompanied by a posse of minders, was offered a seat from Green Park but declined. She said: "We had quite a personal chat, she was asking me about my 13-year-old daughter Jessie and how old she was. It was just so exciting. "She had her arm around me and even moved in when I asked her for a photograph. She was so gracious and so nice that I kept telling her how humble she was, not just because she was on the Tube but because of her manner." Wearing a relatively modest white top for her journey to the Arena, Rihanna left the packed Tube train at North Greenwich station, the Standard said. Flanked by security guards, she then came out of the station and jumped into a waiting car which drove her 100 yards to the backstage area of the huge venue. A spokeswoman for the singer said: "Rihanna decided to get the Tube rather than drive to the first of her 10 sold-out 02 shows". There was no suggestion that a carriage had been reserved or cleared of other passengers. Her journey caught Tube staff and passengers by complete surprise. Last week, farmer Northern Ireland farmer Alan Graham ordered Rihanna off his land when he objected to the singer stripping down to a bikini while filming a new video.